The use of clutches of various types to couple power from a power source such as an engine to auxiliary pieces of equipment is commonly known. Presently, over center mechanical engine clutches are often used to couple the flywheel of an engine to an auxiliary piece of equipment. Such clutches suffer from a number of problems, including pilot bearing failures, excessive wear, frequent adjustment and maintenance, and operator abuse while attempting to achieve engagement when the clutch is coupling the engine with a high inertia load such as in crushers and hammer mills. In view of the state of the prior art, there is a need for a hydraulicly actuated dry multiple disk clutch to serve as a power takeoff unit between the engine and high inertia loads. There is a need in the art for such a power takeoff unit that may easily and effectively be engaged to connect high inertia loads.
It is, of course, most desirable to maintain a dry clutch assembly or power takeoff unit in a package or envelope consistent with SAE standards, such that the size of the hydraulic power takeoff unit is readily adapted for implementation in presently known systems. Moreover, the use of pilot bearings in clutch assemblies and power takeoff units is also known to be extremely problematic. Pilot bearings are generally given to a short life, which is often aggravated by the operational environment of the system, fretting corrosion and the difficulties incident to relubrication. Moreover, pilot bearings are known to result in excessive loads on engine bearings, thus shortening engine life. There is a need in the art for a compact dry power takeoff unit that can be packaged within the constraints of SAE standards, and which provide operational integrity without the implementation of pilot bearings.
Automated engagement controls require engine speed sensors. Since different engines have different numbers of teeth on the flywheel, it is desired to standardize the pulse count by using the drive ring teeth, thus standardizing the control.
The art is further devoid of a simple yet effective structure for precluding inadvertent unsafe rotation of the output shaft and undesired heating and wear within the clutch when the clutch is positioned on a slope or incline.
The art is also devoid of a simple dry clutch with hydraulic activation that incorporates a manifold to control pressure, flow, and actuation time with single drain and supply lines, such that the clutch may be used with any of a variety of power sources.